✍ Scribed by Wilfried Weigel; Sabine Schiller; Hans-Georg Henning
No coin nor oath required. For personal study only.
Irradiation of fl--aminopropiophenones l leads to the formation of 2-aminocyclopropanols 2 which can undergo oxidative ring opening to give enaminones 3. The regioselectivity of cyclopropanol formation of the a-benzyl substituted 1 is determined by the preferred charge transfer interaction between the photoexcited benzoyl chromophore and the amino group. The photocyclizations of the or-or t-substituted 1 proceed stereoselectively. No photoracemization of the pure enantiomers of Ira, independent of the solvent polarity was observed. Aryl or alkyl substituents at the C(3)-or C(2)-ring atom stabilize the cyclopropanol derivatives. Thc formation of 3 indicates regioselective C(I)-C(2) ring opening of 2 probably by localization of the excitation energy.
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## Abstract For Abstract see ChemInform Abstract in Full Text.
A stereoselective route to six and/or five membered ring lactones from optically active y,& epoxy-P-hydroxyesters obtained from nerol and geraniol has been developed. The intramolecular cyclization by epoxide ring opening occurred via activation of 6-endo over the usually favoured 5-exe, and the app